🔍 Key Concepts

• Sea chest design and purpose in a machinery space seawater cooling system • Difference between a drain line (bottom) and a vent line (top) on a sea chest • Regulatory concerns about overboard vs. bilge discharges and load line limitations

💭 Think About

• Ask yourself: where does air naturally collect in a flooded box like a sea chest – at the top or at the bottom? How does that affect whether you use a drain or a vent? • Think about why regulations care about where a line terminates in relation to the deep-draft load line. What risk is being controlled by requiring termination above that line? • Consider whether you ever want a line that is normally open to lead directly into the bilges. What safety or flooding issue could that create?

✅ Before You Answer

• Verify which line (from the top or bottom of the sea chest) is physically suited to remove trapped air, not water. • Check which termination point (above the deep-draft load line vs. into the bilges) is consistent with preventing unintended flooding or contamination. • Confirm that the arrangement allows continuous removal of air without creating a direct path for seawater into the bilges.